Recently, a domestic television set used as the AV device and a display device for use in the OA equipments have been required to have the characteristics such as compactness, thinness, low electric power dissipation, high resolution, and scope enlargement. Thus, the development and practicability have been promoted in the scope enlargement of display devices such as CRTs, liquid crystal displays (LCDs), plasma display devices (PDPs), electro-luminescence display devices, and light emitting diodes (LEDs).
Above all, the liquid crystal display apparatus has the following advantages compared to other display devices: (1) the thickness (depth) can be much thinner, (2) the electric power dissipation can be lower, (3) the full color display can be made easier, and the like. For the reasons, the liquid crystal display apparatus has been recently adopted in many technical fields. It is greatly hoped that the scope enlargement is made.
However, such a scope enlargement results in that the proportion defective, due to the facts such as the burnout of signal lines during the manufacturing process and the defect of pixel, remarkably becomes great, thereby presenting the problem that the price of the liquid crystal display apparatus rises. In order to solve such problems, a single liquid crystal display apparatus is made by connecting with each other a plurality of liquid crystal display panels, so that the scope enlargement is made.
FIG. 15 shows one example of such a liquid crystal display apparatus which is made by connecting with each other a plurality of liquid crystal display panels so as to realize the scope enlargement. In FIG. 15, two liquid crystal display panels 101 and 102 are connected with each other. Each one of the liquid crystal display panels 101 and 102 is provided with two substrates. During the manufacturing process of each one of the liquid crystal display panels 101 and 102, after the two substrates are connected with each other by a seal member 112, the liquid crystal is filled between the two substrates through an opening (filler hole) 113. The seal member 112 is applied for its formation to the peripheral part of the substrate in accordance with the screen printing or the dispenser drawing.
Pixels 106 are provided in a matrix form in the respective liquid crystal display panels 101 and 102. Each pixel 106 is provided with three pixel electrodes 105 which respectively correspond to R (red), G (green), and B (blue) color filters for the color display.
The pixels 106 is driven by TFTs (thin film transistors) 108 which are connected with the respective pixel electrodes 105 (see FIG. 14). The TFT 108 is connected with a scanning electrode 109 and a signal electrode 110 so that each pixel electrode 105 is independently driven. The scanning electrode 109 and the signal electrode 110 are electrically isolated by an isolation film 111.
In the case of a liquid crystal display panel of so-called Cs on Gate structure in which the driving is carried out in accordance with an auxiliary capacitance (Cs) of addition capacitance type which is obtained by overlapping the pixel electrode 105 of one pixel 106 and the scanning electrode 109 of the other pixel 106, the scanning electrode 109 is extended outside the seal member 112 so that the burning test can be made during the manufacturing process of the liquid crystal display panel (see FIG. 14). Note that FIG. 14 shows the structure having no Cs for convenience sake, not the CS on Gate structure. The seal member 112 is applied to the substrate after the formation of the electric wirings such as the scanning electrodes 109 and the signal electrodes 110, so that the seal member 112 crosses the scanning electrodes 109 at crossing part 109a in a plane manner.
For the liquid crystal display apparatus which is made by connecting with each other a plurality of liquid crystal display panels, it is required to improve the displaying quality based on the fact that the part where the liquid crystal panels are connected with each other is noticeable as less as possible. Thus, it is required that the seal member 112 be provided, around the connecting part of the liquid crystal display panels, so as to be close to the pixel 106 (see FIG. 14). In order that the area where the seal member 112 occupies in the connecting part of the liquid crystal display panels becomes as small as possible, it is required that the seal member 112 is formed in accordance with a very fine pattern around the connecting part of the liquid crystal display panels.
According to the .conventional arts, the thermosetting resin is generally used as the seal member. When the thermosetting resin is used as the seal member, it sometimes occurs that the seal shape during the temperature rise is disturbed or the residual solvent exudes. Such occurence is likely to cause the disturbance of the liquid crystal orientation in the range of several hundreds of microns around the seal member. Accordingly, it is not possible to dispose the seal pattern around the pixel. Thus, since it is required that the seal pattern is provided away from the pixel, in the case where the liquid crystal display apparauts is made by connecting with each other a plurality of liquid crystal display panels, the area, where the seal member 112 occupies in the connecting part of the liquid crystal display panels, becomes great. Thus, the connecting part becomes noticeable, thereby causing to deteriorate the displaying quality. For the foregoing reason, the ultraviolet ray hardening resin or the ultraviolet ray hardening resin used in combination with the heat hardening has been used as the seal member.
However, in the case where the ultraviolet ray hardening resin or the ultraviolet ray hardening resin used in combination with the heat hardening is used as the seal member, when the seal pattern is not fine, the area, where the seal member occupies in the connecting part of the liquid crystal display panels, becomes great. Thus, the connecting part becomes noticeable. Accordingly, it is required, around the connecting part of the liquid crystal display panels, that the seal member be formed in accordance with a very fine pattern in the vicinity of the pixel.
The method, wherein the ultraviolet ray hardening resin or the ultraviolet ray hardening resin used in combination with the heat hardening has been used as the seal member of the liquid crystal display panel, has been adopted for the manufacture of small liquid crystal display panels of 1-2 inch-type. In such small liquid crystal display panels, (1) the pixel electrodes and the electric wiring are extremely small and (2) it is required to connect the panel substrates with each other with high accuracy. Accordingly, it is preferable to use the ultraviolet ray hardening resin or the ultraviolet ray hardening resin used in combination with the heat hardening which has little misregistration during hardening of the seal member.
In case of 1-2 inch-type small liquid crystal display panels, when projecting the ultraviolet ray from the ultraviolet ray lamp onto the seal member made of the ultraviolet ray hardening resin or the ultraviolet ray hardening resin used in combination with the heat hardening so as to harden the seal member, the seal member can be accurately hardened in a short time. Since the electric wiring provided in the liquid crystal display panel has a very fine line width of not more than 20 microns, the ultraviolet ray is fully projected even to the seal member on the electric wiring, so that the seal member can be quickly hardened.
In contrast, in case of a single liquid crystal display apparatus made by connecting with each other a plurality of liquid crystal display panels for the scope enlargement, a seal member 6 is provided beneath a black matrix 5 (see FIG. 2 illustrating the present invention) so that the connecting part of the liquid crystal display panels is not noticeable. Such arrangement makes it impossible that the ultraviolet ray is externally projected to the seal member 6 from a substrate side, the substrate being provided with the black matrix 5. Accordingly, the ultraviolet ray must be externally projected to the seal member 6 from the opposite substrate side, the substrate being provided with a TFT.
For the large liquid crystal display panel, it is required to broaden the line width of the electric wiring so as to reduce the time delay of the signal during its propagation. More specifically, in such a case, it is required to provide the electric wiring so that the line width is not less than 20 microns. (1) In case of the liquid crystal display apparatus having a scope of 30-inch or (2) in the case where the electric wiring combines an electrode causing to generate the auxiliary capacitance, it is required to provide the electric wiring so that the line width becomes about 100 microns.
When the line width of the electric wiring is thus broadly provided (about 100 microns) in the liquid crystal display panel, even if the ultraviolet ray from the ultraviolet ray lamp is projected onto the seal member 112 made of the ultraviolet ray hardening resin or the ultraviolet ray hardening resin used in combination with the heat hardening, it is impossible to fully project the ultraviolet ray onto the electric wiring, i.e., onto the seal member 112 on the crossing part 109a of the scanning electrode 109 (see FIG. 14). Thus, it is likely that the inadequate hardening of the seal member 112 occurs. Further, the problem is presented that (1) when the liquid crystal is filled through the opening 113 between the two substrates under vacuum, the liquid crystal is not fully filled since a predetermined vacuum level is not kept inside the liquid crystal cell due to such an inadequate hardening of the seal member 112, or (2) the liquid crystal orientation in the vicinity of the seal member 112 is disturbed.
In the case where the electric wiring has such a broad line width, even the seal member on the electric wiring may be hardened to a degree by projecting the ultraviolet ray for a long time. However, in such a case, the liquid crystal display panel absorbs the ultraviolet ray and is thus heated up, thereby causing the occurrence of the distortion.
According to the foregoing conventional liquid crystal display apparauts made by connecting with each other a plurality of liquid crystal display panels, when the seal member is provided in the vicinity of the pixel so that the connecting part is not noticeable, it is likely that (1) the liquid crystal orientation was disturbed due to the inadequate hardening of the seal member and (2) the inadequate filling of the liquid crystal occurred. Thus, it has been impossible to accurately provide the fine line seal member in the vicinity of the pixel.
Even in the liquid crystal display apparatus having a single liquid crystal display panel, it is sometimes required that the seal member be provided in the vicinity of the pixel during the manufacturing process of the liquid crystal display panel. More specifically, it is recently required to enlarge the display area in the liquid crystal display apparatus having a predetermined dimension as is often seen in a liquid crystal module, having a limited casing, for use in a note-type personal computer. Since the maximum module dimension of the liquid crystal display panel which can be accommodated in the note-type personal computer having a predetermined outline is almost determined, it is required to broaden a bit further the display area of the liquid crystal display panels within the limited module outline. The broadening of the pixel area of the liquid crystal display panel necessitates that the seal member be provided in the vicinity of the pixel during the manufacturing process of the liquid crystal display panel.
However, in such a case, like the foregoing liquid crystal display apparatus made by connecting a plurality of liquid crystal display panels, it is most likely that the inadequate hardening of the seal member occurs in the area where the seal member crosses the electric wiring such as the scanning electrodes or the signal electrodes. In addition, in the area where the seal member crosses the electric wiring, it is most likely that the seal member is seeped out or the pattern of the seal member is disturbed (later described). Such seeping of the seal member and disturbance of the pattern of the seal member causes the seal member to erode the pixel area, thereby resulting in that the displaying quality of the liquid crystal display apparatus is deteriorated.
As mentioned above, in the liquid crystal display apparatus having a single liquid crystal display panel, when the seal member is provided in the vicinity of the pixel so as to broaden the display area, it was observed that the inadequate hardening of the seal member occured, the seal member was seeped out, and the pattern of the seal member was disturbed. Thus, it was impossible to accurately provide the seal member in the vicinity of the pixel.